Heating appliance



July 21, 1936. H. w. SANFORD HEATING APPLIANCE Filed Sept. 27, 1952 ling/L Patented July 21', 193

OFFICE This invention relates to heating appliances, and more cularly concerns an arrangement of the structure of the appliance whereby a maximum heating efiect is produced upon a fluid in motion-with a minimum consumption of fuel.

' One of the features of the present invention is the provision of a heated wall and a second wall spaced from the heated wall and providing a chamber within which a fluid may move while being heated, together with means for producing a swirling motion of the fluid in said space so that the various parts of the fluid are successively brought into contact with the heated wall to absorb heat therefrom.

Another feature of the present invention is the provision of an upright heated wall together with a second upright wall .spaced from said heated wall and providing therewith a venturi with spacings of between two and five inches, preferably about two and one-half inches at the closest point, these walls being smooth and free from horizontal projections which might obstruct the free upward movement of a fluid between the walls, together with means for causing a 1- 25 ing motion of the fluid while moving in said space.

A further feature of the present invention is the provision, in conjunction with ed walls of which at least one is heated, of means for admitting air to the space between these walls adjacent the bottom thereof, this air being caused to travel in streams angularly directed with respect to one another whereby a swirling of the air is produced in the space between the walls 35 during the upward movement of the air in this space.

Still another feature of the present invention is the provision of two upright walls of which at least one is heated, together with deflector means located between the walls and operating to cause a swirling of air in motion between the walls.

A still further feature of the present invention is the provision of upright walls having their op- 45 posed surfaces of zigzag term in the vertical plane,

at least one of the walls being heated, together with means for admitting air to the space be-,

tween the walls wherein the zigzag formation of the surfaces produces a swirling of the air in 50 its movement between the surfaces.

With these and other objects in view as will appear in the course of the following specification and claims, illustrative forms of practicing the invention are set forth on the accompanying s drawing, in which:

Figure l is a front elevation of a circulating heater for air in which is embodied one form of construction of the present invention.

Figure ,2 is a diagrammatic view showing a pair of upright walls with a spiral deflector there- 5 between.

Figure 3 is a similar view, with the provision of two vertically spaced deflectors in the space between the walls.

Figure 4 is a perspective view, on a larger scale, showing one of the deflectors illustrated in Figure 3.

In Figure l, the circulating heater is shown to comprise-the base it upon which is seated the ash pit section ii having a. guard i2 thereon. The flre box section It is seated and sealed at the upper. end of the ash pit section, and in turn is in sealing relationship with the combustion section it. A top hood member It has an outlet it which leads, as usual, to a chimney or like flue for the evacuation of products of combustion.

It will particularly be noted that there are no external horizontal projections from any of these members, but that they provide a smoothupright surface which is heated during the operation of the heater and which does not obstruct the free upward flow of the fluid, here air, which is in contact with these suri'aces. Thus a rapid movement is imparted to the air by thermal con- 0 vcction.

Externally of and spaced from the heated wall provided by these members is -a jacket l1 constituting a second upright wall located at a distance of substantially two to five inches from 5 the flrst upright wall, in the heater of the presently illustrated. type which operatesupon air.

It has been found by practical tests that where the distance is much less than two inches, an impedance or obstruction to the flow of air is 40 produced which reduces the efllclency of the structure, apparently by blockage or throttling of the air current; and on the other hand if the distance is increased much above four and onehalf inches, the benefits of the hereinafter described swirling efiectsare lost, and again the emciency is low. In these actual tests, it has been found that the efllciency is at a maximum when the distance is between two and flve inches.

The upright walls I1 and the upright wall pro- 5 vided by the members II, I: and I are preferably slightly divergent upwardly to provide for a slight expansion of the air as it is heated. At the lower edge of the second upright wall ll, it is joined with a skirt II which has a downwardly 5 the heated upright wall. The two upright walls thus preferably have a relative divergence at their lower portions and upper portions, with a throat between the upper and lower extremities, so that a venturi is formed having a throat dimens'ion of approximately two and one-half inches, and a spacing at the top of approximately three to four inches. The spacing at the bottom should be of the order or four or four and onehalf inches as a minimum.

Surrounding the jacket or second upright wall i1 is an external housing l 9 which may be of any desired shape for providing the external appearance desired, and is provided, for example, in front with closing doors 29 which cover and conceal internal doors, as usual, provided for the firing opening 2| and an ash pit opening 22 in the members it and ii respectively.

Openings 23 are illustrated in the base section IQ for the admission of relatively cold air from adjacent the floor of the apartment in which the heater is located, and in addition thereto, the lower portions of the housing l9 are provided with louvres 25 which admit air to a point beneath the skirt l8 and also to a point above this skirt.

The top of the housing It is closed by a perforatedcover or cap 25.

In operation, the bed of coals on the grate it directly heats a portion of the wall of the fire box i3, and the combustion products serve to heat the walls of members it and It. This heated wall is presented to the 'air located in the space between the same and the second upright wall II. The heated air, by expanding, becomes .of lesser density'than the air of the compartment, and moves upwardly by thermal convection and passes out through openings in the cover 25,

its place being taken by colder air flowing in heated surface, so that the various portions of the colder air are successively brought into contact with the heated .surface. Since the rate of transfer of heat from a surface is an exponential function of the difference of temperatures of the air and the heated surface, the heat transfer from the heated wall occurs more rapidly than would be the case with a steady upward flow of air along the surface of the wall. It has been found that the provision of a second upright wall, with a restricted space between the same and the upright heated wall, leads to a continuance of this swirling action, and hence to a very rapid heat transfer, and hence a high efficiency of the device, since it is not necessary to have "the walls of members l3, it, for example, heated to as high a temperature as heretofore on the one hand, and to a greater quantity of heat transfer when the walls of said members are heated to a given temperature. This increase in emciency may be theoretically considered as arising through the increase in the velocity of the moving air, the greater temp ature diiference ber asses diverging relationship to the oppositeportion of therewith, the greater transfer of heat from the wall to the air and therewith a greater temperature differential between the combustion gases and fuel to this wall, so that less fuel is required for a given heating and the flue gases 5- are maintained at a lower temperature as greater heat values are extracted therefrom than with theusual type of arrangement. In particular, it is pointed out that the smooth external surface prevents pocketing or stagnation of air adjacent the heated wall with the temperature of air in these pockets increased to approximately the temperature of the wall, and the air in these pockets serving as an insulator, so to speak, to prevent proper heating of other portionsof the upwardly flowing air current. Further, the lower temperature of the heated wall with the present structures results in a lesser tendency toward burning of such a wall, and hence in a greater life of the heater.

In tests made with devices, it was found that an eficiency of around seventy-five to eighty percent was obtained from a stove so constructed, with a spaced second wall, in comparison to the efiiciency of forty-nine percent of the usual we arrangement without employment of the Venturi principle, smooth walls, and the selected spacing. In two test runs, the efliciences were 79 percent and 83.5 percent.

The passage of air upward between the second 30 upright wall I? and the housing is likewise leads to a heating effect upon this air, which then Joins with the air from the inner space between the first and second aforesaid walls, and operates within and immediately above the cover 25 to 35 cause a mingling or diifusion,'and thus effect a greater spreading and slowing down of the heated air column, so that the heater does not have a great tendency, as heretofore, to cause soiling of thewall and ceiling.

In the form of construction illustrated in Figure 2, the heated wall is and the second wall l'la. provide a space between them in which is located a spiral deflector 80 which operates to produce a swirling of the air so that the various 4 parts thereof are successively brought into contact with the surfaces of the heated wall Ila.

In the form shown in Figure 3, the heated wall Nb and the second wall I'll) provide a space between them in which are located a pair of deflectorsil which are vertically spaced with respect to one another and are shown in detail in Figure 4 as comprising, in this illustrative form, a rectangular frame 32 which is open at the top and bottom and may be connected to both the heated wall Nb and the secondwall I lb to sustain the latter wall in position. Within the frame 32 is a deflector member 38 having trapezoidal walls 84 which are parallel to walls of the frame, and each of which is provided at its free G edge with a deflector piece 35 or 36, which are angularly directed and-serveto produce a swirling movement (here about a vertical axis) of a part of the aircurrent from adjacent the heated wall toward the second wall, or vice versa; and 5 thus produce a swirling of the air with the same results as before.

In the form illustrated in Figure 1, the upright wall I! is substantially vertical, while the external surface of the heatedwall by members It, ll so is slightly convergent upwardly, although ob viousiy this is not required for the practice of the invention. In each instance, it will be noted that advantage is taken of the fact that the transfer of I heat at a contacting surface is greatest when the.

speed of relative movement is greatest. When a fluid is moving in contact with a heated wall, the rate of transfer increases with increasing relative velocity of the fluid. With the present structure, the swirling motion results in the greater I speed of movement past a given point on the wall, than the general upward rate of flow of the fluid. Thus, when the heating appliance is first brought into operation, there is little or no draft between the two walls. As the rate of draft builds up, the whirling motion itself increases, and thus the rate of transfer of heat is increased, and a greater and greater draft effect is produced, which in turn produces a greater rate of whirling. The effect therefore is cumulative, and the emciency is increased not only by the greater volume of fluid being passed through the appliance, but also by the more effective conditions of transfer, and the feasibility of yielding a given number of heat units to a relatively larger volume of fluid.

By comparison, without this whirling motion, the fluid would pass directly upward along a heated wall, and this layer of fluid would be highly heated while adjacent colder layers would not come in contact with the heated surface'at all, being insulated therefrom by the hot layer.

The device therefore operates by an actively produced convection occurring'locally adjacent the heated surface, with the heating of all parts of the flowing column by contact with the heated,

' by thermal convection, this column of fluid being cut off by a second upright wall spaced from the heated wall.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent, is:

1. A heating appliance having a first upright wall and a second upright wall spaced from said first wall, said walls providing a smooth and substantially unobstructed upward passage space for heated air, a bottom alr'inlet to the space between said walls, a'top air outlet from the space between said walls and located above said inlet, means for highly heating a portion of one of said walls, and deflector means in said space for producing swirling movements toward and from said highly heated portion within the column of airmoving upwardly in said space.

2. The method of producing a transfer of heat from an upright heated surface to a fluid, which comprises contacting a substantially vertical column of fluid with the surface, introducing fluid into, through and from said column.

umn of fluid with the surface, introducing fluid into said column at the bottom thereof, highly heating a portion of said surface, and producing swirling motions of the fluid at the level of said highly heated portion whereby to remove heated 5 fluid from contact with saidsurface and to bring fluid heated to a lesser degree into\ contact with said surface while effecting the free and substantially unobstructed thermally induced movement of fluid into, through and from said column. 10

4. A heating appliance having an upright wall, means for highly heating a localized portion of said wall near its bottom, a second upright wall spaced from said heated wall, said walls provid ing a smooth and substantially unobstructed upward passage space for heated air, an air inlet to the space between said walls, an air outlet from the space between said walls and located above said inlet, and means cooperative with the walls including a skirt on said second wall extending below said highly heated portion from the level of said highly heated portion for causing the air to assume a swirling motion upward and away from the heated wall during its up ward movement in said space, said skirt and the opposite portion of said heated wall being directed downwardly divergent with respect to one another.

5. A heating appliance having opposed smooth walls for providing a restricted space within 30 winch air may move upwardly rapidly in a substantially unobstructed manner, means for highly heating a, localized portion of one said wall at the level of said throat, said walls including portions which are so spaced as to form a venturi having a throat diameter of 2 inches for ac-' celerating the air movement adjacent the heated wall, and air inlet and outlet means to the space between said walls, said venturi and the heating thereat causing the air to change direction from its thermally induced upward course and thereby producing a swirling so that the air adjacent the heated wall moves upwardly and away from the heated wall to bring cooled air into contact with said heated wall.

6. A heating appliance having a smooth upright wall having a highly heated portion, a second smooth upright wall spaced. from said heated wall, said walls providing a smooth and substantially unobstructed upward passage space for heated air, an air inlet to the space between said walls located at a low level, an air outlet from the space between said walls located at a high level, and means cooperative with the walls for causing local swirling of the air upward and away from said highly heated portion as it moves upwardly in said space during its general upward movement so that the swirling air is heated from said first wall and all parts of the air antering the inlet are brought into and out of con- 50 tact with said heated wall for effecting a rapid transfer of heat from said highly heated portion and accelerating thethermal movement of air in said space.

7. A heating appliance having a first upright 55 wall, means for highly heating a localized portion of said wall near its bottom. a second upright wall spaced from saidflrst wall, said walls providing a smooth and substantially unobstructed upward passage space for the upward 7 movement of heated fluid by thermosiphon action, a bottom fluid inlet to the space between said walls, a top fluid outlet from the space between said walls, said walls also providing means below the level of the highly heated por- 75 4- aoaaau tion for causing fluid to enter said passage space in directions at an angle to one another for causing a swirling movement thereof at the level of the highly heated portion upward and away from the said'highly heated portion so that all parts of the fluid are brought into and out of contact with said heated portion rapidly for effecting a rapid transfer of heat from the wallv and accelerating the thermal movement of the fluid in said space. I

8. A circulation heater having anupright wall and including a tire bowl for highly heating a restricted portion of said upright wall. a second upright wall spaced from said first upright wall, an air inlet for admitting air between said walls at the bottom, an air outlet for discharging air from between said walls at the top, said inlet. outlet and walls providing a smooth and substantially unobstructed upward passage for air,

and means cooperative with the walls for pro- 5 

